JP4516021B2 - SC cut crystal unit - Google Patents

Description

  The present invention relates to an SC cut crystal resonator, and more particularly to an SC cut crystal resonator having a shape capable of obtaining good vibration characteristics.

  Conventionally, as a twice-rotated crystal unit, for example, as shown in FIG. 3, a plane orthogonal to the Y-axis of the crystal of the crystal is rotated about 33 ° around the X-axis, and the Z-axis There is known an SC-cut crystal resonator in which an electrode is formed on a crystal piece 1 cut out from a surface rotated about 22 ° around the center (see, for example, Japanese Patent Application Laid-Open No. 11-177376).

  This SC-cut quartz crystal has a temperature characteristic of a cubic curve similar to that of an AT-cut, and its inflection point is around 94 ° C. It is used as a crystal unit for oscillators.

  However, as shown in FIG. 4, the SC-cut crystal resonator has a B mode (in the vicinity of C-mode resonance (indicated by symbol C in FIG. 4)), which is the main vibration, on the high frequency side. B) and A mode (indicated by A) side vibrations.

  Here, since the value of the equivalent resistance (hereinafter abbreviated as “CI”) of the vibration in the A mode is larger than the CI in the C mode, it is difficult for the oscillator to output a signal. Don't be.

  On the other hand, the CI of the vibration in the B mode is equal to or smaller than the CI of the C mode, and the frequency is approximately 1.09 times that of the C mode and is close to each other. . For this reason, when an oscillator is actually manufactured, it often oscillates in the B mode, which is a secondary vibration.

  Therefore, when using an SC-cut crystal resonator, the B-mode CI is made larger than the C-mode CI so that the B-mode vibration can be suppressed in order to surely excite the C-mode vibration. It is necessary to keep. For this reason, B-mode vibration is suppressed by adding mass to suppress the unnecessary vibration to the plate surface of the crystal piece or by devising its holding position.

  However, in order to sufficiently suppress the vibration of the B mode, it is necessary to repeat trial and error, which is troublesome and the reproducibility is very poor.

  The SC-cut crystal resonator of the present invention has been made in view of the problems of such a conventional SC-cut crystal resonator. By cutting and processing the external shape of the crystal piece into a special shape, An object of the present invention is to provide an SC-cut crystal resonator capable of suppressing resonance in the B mode reliably and with high reproducibility.

The SC-cut quartz resonator of the present invention rotates a plane perpendicular to the Y-axis of the crystal of crystal from about 33 ° to 35 ° about the X-axis, and from this rotated position to about 22 ° to about the Z-axis. The end face perpendicular to the Z ′ axis of a rectangular crystal piece elongated in the X′-axis direction cut out from the surface rotated by 24 ° was rotated + 7 ° to + 13 ° or −7 ° to −13 ° around the X ′ axis. It is characterized by tilting in the direction. Further, the SC-cut crystal resonator is characterized in that the tilt angle is −9 ° to −11 ° or + 9 ° to + 11 ° .

  Since the SC-cut crystal resonator of the present invention is processed so that the end face in the longitudinal direction of the strip-shaped SC-cut crystal piece is inclined, the vibration of the B-mode of the present invention can be suppressed and the inflection point temperature can be reduced even if the shape is reduced. No change occurs. Therefore, it is possible to provide an SC-cut crystal resonator that is easy to design and manufacture an oscillator, can obtain good oscillation characteristics, and is inexpensive.

  FIG. 1 is a perspective view showing the cutting angle of the SC-cut quartz plate of the present invention.

  FIG. 2 is a perspective view of a crystal piece cut out from the crystal plate shown in FIG.

  FIG. 3 is a perspective view showing a cutting angle of a conventional SC-cut quartz plate.

  FIG. 4 is a graph showing resonance characteristics of a conventional SC-cut crystal resonator.

  An embodiment of an SC cut crystal resonator according to the present invention will be described below with reference to the accompanying drawings.

  FIG. 1 is a perspective view showing a cutting angle of a crystal piece 1 used in an SC-cut crystal resonator according to the present invention.

  That is, here, the plane orthogonal to the Y axis of the crystal of the crystal is rotated 33 ° to 35 ° about the X axis as the rotation center, and is rotated 22 ° to 24 ° about the Z axis from the rotated position.

  When such two rotations are performed, the XZ plane orthogonal to the Y axis in FIG. 1 becomes the Z′-X ′ plane. As described above, when the X-axis is rotated 33 ° to 35 ° around the rotation axis and the Z-axis is rotated about 22 ° to 24 ° from the rotated position, excitation is performed as a so-called SC-cut crystal resonator. can do.

  Then, as shown in FIG. 2, a strip-shaped quartz crystal piece 1 elongated in the X′-axis direction is cut out from the crystal plate on the Z′-X ′ plane. Then, a tilting process is performed on an end face in the longitudinal direction of the crystal piece 1, that is, an end face (X'-Y 'face) perpendicular to the Z' axis.

  The angle at which this end face is tilted is tilted in the direction rotated by + 7 ° to + 13 ° or −7 ° to −13 ° around the X ′ axis, and the end face of the crystal piece 1 thus tilted is X′−. Y ”plane.

When the angle at which the end face is inclined is + 7 ° to + 13 ° or −7 ° to −13 °, a good B-mode suppression effect can be obtained. More preferably, the angle of inclination is ± 9 ° to ± 11 ° .

  In the case of manufacturing a crystal resonator from such a crystal piece, a pair of excitation electrodes are formed facing the plate surface of the crystal piece. Then, the crystal piece is housed in a predetermined container and held by an appropriate holding means, and the excitation electrode is led out to constitute a crystal resonator.

  By cutting the outer shape of the crystal piece in this way, contour slip vibration can be suppressed. The B-mode vibration, which is a particularly harmful sub-vibration, is a vibration of the contour slip vibration system. However, the SC-cut crystal resonator of the present invention can suppress the B-mode vibration and the C-mode vibration, which is the main vibration. Can be surely excited.

  That is, in a crystal piece having a rectangular SC shape elongated in the X′-axis direction, an end face orthogonal to the Z′-axis is tilted by −10 °, the B-mode CI is compared with a crystal piece that is not inclined. Increases about 50%, while B-mode vibration is significantly suppressed.

  Therefore, it is possible to reliably suppress harmful B-mode vibration which has been the biggest obstacle in the past when using an SC-cut crystal resonator, and to provide a useful oscillator without using special processing or a special oscillation circuit. Be able to get.

  Furthermore, the inflection point temperature 94 ° of the SC-cut quartz crystal resonator is a phenomenon that shifts to the high temperature side when the crystal piece is miniaturized. Therefore, when the oscillator is assembled, the set temperature of the thermostat is set. It was difficult. However, when the crystal piece of the present invention having an inclined end face as shown in FIG. 2 is used, even if the shape of the crystal piece is reduced, the inflection point temperature of the crystal unit is kept at 94 ° and the temperature increases. It will not be displaced.

As described above, the SC-cut crystal resonator of the present invention is useful as a crystal resonator of a thermostat crystal oscillator, and in particular, it can surely excite C-mode vibration by pressing B-mode vibration. Suitable for use in crystal oscillators.

Claims (2)

A plane orthogonal to the Y axis of the crystal of crystal is rotated 33 ° to 35 ° around the X axis, and the X ′ axis is cut out from a plane rotated from 22 ° to 24 ° about the Z axis from this rotated position. A strip-shaped quartz piece elongated in a direction is formed, and an end face perpendicular to the Z ′ axis of the quartz piece has an inclination angle inclined in a direction rotated by + 7 ° to + 13 ° around the X ′ axis. SC cut crystal resonator. A plane orthogonal to the Y axis of the crystal of crystal is rotated 33 ° to 35 ° around the X axis, and the X ′ axis is cut out from a plane rotated from 22 ° to 24 ° about the Z axis from this rotated position. A rectangular crystal piece that is elongated in the direction, and has an inclination angle in which the end face perpendicular to the Z ′ axis of the crystal piece is tilted in a direction rotated by −7 ° to −13 ° about the X ′ axis. A featured SC cut crystal unit.

Images